Monarch Instrument DC 2000 - Manual (Page 42)

Page 3-12
Chapter 3 Getting Started
The input to any channel in the conditioning block can be any one of the base points, or it can be the live inputs.
Live inputs can have input and output scaling applied in the conditioning block unless this is predefined by the
nature of the input, i.e., thermocouples. An example of input/output scaling is given in section 3.5.
The outputs of the conditioning block are also the values represented in the Digital Windows and are real-world
engineering values. The outputs of the conditioning block are also fed through to a scale block where a chart
scale is applied to each point. The chart scales determine what part of the full scale range will be used by the
display/record block. There are two sets of 8 scales available to the user. The second set is an alternate set which
can be applied to the base points in place of the normal set when triggered by an external event. Each chart scale
may be applied to any one or more of the base points to provide an output scaled point. These scale points are
then applied to the display/record block which consists of the visual information or recorded information that the
user requires. Up to twelve scaled points are applied to the bar graph display. Up to twelve may be displayed on the
chart and up to fifteen may be recorded to disk. Note that points recorded to disk need not be the same as points
displayed on the bar graph or the chart, however, in the case of the chart, any point which is not recorded to disk will
have limited browse capability. The user should also be aware that applying scaling other than full scale output to
recorded data, limits the data to the range between scale endpoints. It is possible to store the base point with
different scaling than is used to display it on the chart using one of the computational channels.
3.5 Using Chart Scales
To better understand the use of input and output scaling, and how scaling base points affects the data, consider the
following example, highlighted by Figure 3-14.
Figure 3-14 Scaling Example
Assume the user wants to record the output from a pressure transducer which gives a 0 to 5 volt DC output signal.
This coincides to a pressure of 0 to 3000 pounds per square inch (PSI). The process being monitored typically runs
at 2200 PSI ±10%, this is the area of interest. The output of the transducer which peaks at 5 volts is connected to
live input channel 1 and the 12.5 volt full-scale range is selected to cover this range. Since the maximum input
voltage will be only 5 volts on a 12.5 volt range, use the input scale option to set the low end at 0.0, and the high
end at 5.000 volts. To convert this directly to PSI, the output scale is set at low point 0.0 and high point 3000.0.
The base point now becomes 0 to 3000 for an input of 0 to 5 volts, scaled linearly across the range. The engineer-
ing units can be set to PSI and the point tag can be set to any label that identifies the process. All of this is
accomplished in the Points menu - Section 5.6. Apply scale A to the base point, this too is selected in the Points
menu.